The endogenous cholinergic neurotransmitter, acetylcholine, exerts its biological effect via two types of cholinergic receptors, the muscarinic Acetyl Choline Receptors (mAChR) and the nicotinic Acetyl Choline Receptors (nAChR).
It is well established that muscarinic acetylcholine receptors are of importance in relation to memory and cognition, and much research aimed at the development of agents for the treatment of memory related disorders have focused on the synthesis of muscarinic acetylcholine receptor modulators.
Nilsson et al [Nelsson BM, Sundquist S, Johansson G, Nordvall G, Glas G, Nilvebrant L & Hacksell U; J. Med. Chem. 1995 38 473-487] describe the synthesis and muscarinic activity of certain 3-heteroaryl substituted quinuclidin-2-ene derivatives including 3-(2-benzofuranyl)quinuclidine-2-ene, 3-(3-benzofuranyl)quinuclidine-2-ene, 3-(2-benzothienyl)quinuclidine-2-ene, 3-(3-benzothienyl)quinuclidine-2-ene, 3-(2-benzoxazolyl)quinuclidine-2-ene, 3-(2-benzthiazolyl)quinuclidine-2-ene, 3-(2-benzofuranyl)-quinuclidine and 3-(2,3-dihydrobenzofuran-2-yl)quinuclidine.
Nordvall et al. [Nordvall G, Sundquist S, Johansson G, Glas G, Nilvebrant L & Hacksell U; J. Med. Chem. 1996 39 3269-3277] describe the synthesis and muscarinic activity of certain quinuclidine-2-ene derivatives including 3-(2-benzofuranyl)-quinuclidine-2-ene and 3-(2-furo[3,2-b]pyridinyl)quinuclidine-2-ene.
Johansson et al. [Johansson G, Sundquist S, Nordvall G, Nilsson B M, Brisander M, Nilvebrant L & Hacksell U; J. Med. Chem. 1997 40 3804-3819] describe the synthesis of certain quinuclidine-2-ene derivatives useful as muscarinic antagonists.
Recently, however, an interest in the development of nicotinic acetylcholine receptor modulators has emerged. Several diseases are associated with degeneration of the cholinergic system, i.e. senile dementia of the Alzheimer type, vascular dementia and cognitive impairment due to the organic brain damage disease related directly to alcoholism. Indeed several CNS disorders can be attributed to a cholinergic deficiency, a dopaminergic deficiency, an adrenergic deficiency or a serotonergic deficiency.